Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <iostream>
#include <queue>
#include <utility>
using namespace std;
int h,w;
char c[50][50];
int d[50][50];
int num;
int X[4]={0,-1,0,1},Y[4]={-1,0,1,0};
int main(){
    cin>>h>>w;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cin>>c[i][j];
            if(c[i][j]=='.')num++;
        }
    }
    d[0][0]=1;
    queue<pair<int,int>> que;
    que.push(make_pair(0,0));
    while(!que.empty()){
        pair<int,int> p=que.front();
        que.pop();
        int x=p.first,y=p.second;
        for(int i=0;i<4;i++){
            int nx=x+X[i],ny=y+Y[i];
            if(nx<0||h<=nx||ny<0||w<=ny||c[nx][ny]=='#'||d[nx][ny]!=0)continue;
            d[nx][ny]=d[x][y]+1;
            que.push(make_pair(nx,ny));
        }
    }
    if(d[h-1][w-1]==0)cout<<-1<<endl;
    else cout<<num-d[h-1][w-1]<<endl;
    return 0;
}